Self-stabilizing pressure compensated injector

ABSTRACT

A construction for stabilizing pressure conditions in a combustion chamber, in flow passages, or the like, utilizing fluid amplifier principles to achieve the desired stabilization. The passages carrying fuel or oxidizer, or both types of passages, are formed with diverging outlet portions and these outlet portions are provided with auxiliary passages located so as to respond to abnormal local pressure conditions and to control the flow of fluid through said outlet portions in a manner to compensate for the abnormal local pressure conditions. In one form, the auxiliary passages are exposed to the interior of a combustion chamber at points spaced from the outlet ports and sense abnormal local pressure conditions in the regions of the ports, operating as fluid amplifiers to produce compensating flow conditions in the fluid traversing the diverging passages. In another form, the auxiliary passages are in the walls of a burner, by-passing parts of the main diverging outlet passage portions and acting to oscillate the outlet streams between the outlet passage portions, greatly increasing the fuel surface area exposed to the oxidant, creating substantial turbulence, and, thereby improving combustion efficiency and reducing pollution of the surrounding environment.

United States Patent 1 1 Qole et a1.

[ July 31, 1973 1 SELF-STABILIZING PRESSURE COMPENSATED INJECTOR [76]inventors: Larry E. Cole, 13042 Cherbourg St.,

New Orleans, La. 70129; John M. Zabsky, 242 W. Franklin, Apt. 405,Minneapolis, Minn. 55404 22 Filed: Dec. 5, 1969 211 Appl. No.: 882,583

[52] US. Cl. 60/39.65, 123/119 R, 123/32 R, 60/258, 60/39.74 R, 60/39.74A, 60/39.72 R

[51] Int. Cl. F02g H00 [58] Field of Search 60/39.74, 39.23, 60/258,39.65; 123/119 R; 137/815 Primary Examiner-Samuel FeinbergAttorneyBerman, Davidson & Berman [57 ABSTRACT A construction forstabilizing pressure conditions in a FZ/EL UNDER P2555021:

combustion chamber, in flow passages, or the like, utilizing fluidamplifier principles to achieve the desired stabilization. The passagescarrying fuel or oxidizer, or both types of passages, are formed withdiverging outlet portions and these outlet portions are provided withauxiliary passages located so as to respond to abnormal local pressureconditions and to control the flow of fluid through said outlet portionsin a manner to compensate for the abnormal local pressure conditions. Inone form, the auxiliary passages are exposed to the interior of acombustion chamber at points spaced from the outlet ports and senseabnormal local pressure conditions in the regions of the ports,operating as fluid amplifiers to produce compensating flow conditions inthe fluid traversing the diverging passages. ln another form, theauxiliary passages are in the walls of a burner, by-passing parts of themain diverging outlet passage portions and acting to oscillate theoutlet streams between the outlet passage portions, greatly increasingthe fuel surface area exposed to the oxidant, creating substantialturbulence, and, thereby improving combustion efficiency and reducingpollution of the surrounding environment.

17 Claims, 13 Drawing Figures M/A/ AasM/G F 1.0/0 Use/420702 /33 P02 rsCbMBusT/a/v $2905 70 /3 9 TdfiEl/VE fill SELF-STABILIZING PRESSURECOMPENSATED INJECTOR This invention relates to means for stabilizingpressure conditions in combustion chambers, flow passages, or the like,and more particularly to pressurestabilizing devices employing fluidamplifier principles.

The main object of the invention is to provide a novel and improvedstructure for stabilizing pressure conditions in a combustion chamber orsimilar enclosure carrying fluid to prevent instability of pressure inthe combustion chamber or enclosure and to thereby prevent roughoperation of the associated device or damage or destruction thereof, theimproved pressure-stabilizing means involving relatively simplestructural components and acting to efficiently sense and to eliminateabnormal local pressure conditions in the combustion chamber orassociated flow passage and responding in a manner to quickly andefficiently compensate for the abnormal local pressure conditions.

A further object of the invention is to provide an improved structuralarrangement for stabilizing pressure conditions in a combustion chamber,flow passage, or the like, said arrangement operating on the principlesemployed in fluid amplifiers to detect abnormal local pressureconditions and to react thereto in a manner to dissipate such abnormalconditions, the arrangement producing good combustion efficiency, whenemployed in a combustion chamber, preventing the development ofundesirable or destructive pressure waves in the chamber, and acting toredistribute fluids in the chamber to break up a pressure wave.

A still further object of the invention is to provide an improved meansfor stabilizing pressure conditions in combustion chambers, flowpassages, or similar enclosures through which fluid passes or in whichfluid is admitted for combustion, the stabilizing means involving nomoving parts, being highly sensitive to the presence of abnormal localpresssure conditionsin the associated chamber or enclosure, andproviding a quick compensating action which automatically redistributesthe fluid in such a manner as to remove the abnormal pressure condition.

A still further object of the invention is to provide an improved fluidamplifier device for facilitating combustion in a fuel burner, thedevice operating to oscillate the stream of fuel entering the combustionchamber of an associated burner assembly in a manner to greatly increasethe available fuel surface area exposed to the oxidant combining withthe fuel in the process of combustion, whereby the combustion isaccomplished very rapidly and with high efficiency and wherein the fuelis mixed into the oxidizer rather than the oxidizer being mixed into thefuel, as in conventional devices, the arrangement thus providing higheconomy in the utilization of fuel as well as greatly improved stabilityof operation.

A still further object of the invention is to provide an improved fluidamplifier device for facilitating combustion in a fuel burner in anefficient manner so as to reduce the amount of condensed carbon andincomplete products of combustion, thereby reducing pollution of thesurrounding environment and providing a safety benefit.

Further objects and advantages of the invention will become apparentfrom the following description and claims, and from the accompanyingdrawings, wherein:

FIG. 1 is a longitudinal vertical cross-sectional view taken through thecombustion chamber and thrust chamber assembly of a pressure-fed orpump-fed rocket engine employing improved means for stabilizing pressureconditions in the combustion chamber in accordance with the presentinvention.

FIG. 2 is an enlarged fragmentary horizontal crosssectional view takensubstantially on the line 2-2 of FIG. 1.

FIG. 3 is a fragmentary vertical cross-sectional view takensubstantially on the line 33 of FIG. 2.

FIG. 4 is a somewhat diagrammatic view of an improved fluidstream-oscillatingburner constructed in accordance with the presentinvention and employing the fluid amplifier principles of the invention.

FIG. 5 is a fragmentary vertical cross-sectional view taken through theupper portion of an internal combustion engine cylinder provided withturbulence generating means according to the present invention employedbetween the fuel supply manifold and the combustion chamber portion ofthe cylinder.

FIG. 6 is a fragmentary cross-sectional view taken through the wall of atypical multi-unit burner assembly employing gas stream-oscillationmeans similar to that shown in FIG. 4 and employing fluid amplifierprinci' ples according to the present invention.

FIG. 7 is a diagrammatic cross-sectional view taken through a typicalsteam or air atomization burner employing fluid amplifier principlesaccording to the present invention.

FIG. 8 is a diagrammatic cross-sectional view of another form of atypical steam or air atomization burner employing fluid amplifierprinciples according to the present invention, and representing amodification of the structure of FIG. 7.

FIG. 9 is a generally diagrammatic cross-sectional view showing anothertypical form of a fuel burner employing fluid amplifier principlesaccording to the present invention and including an aspirated orinjected primary air supply means.

FIG. 10 is a diagrammatic view similar to FIG. 4 but showing a modifiedform of fluid stream-oscillating burner according to the presentinvention, designed to produce increased tubrulence.

FIGS. ll, 12 and 13 are diagrammatic longitudinal verticalcross-sectional views showing the application of fluid amplifierinjectors of the present invention to jet engines.

In explaining the theory of operation of the present invention, it willbe useful first to consider typical devices to which the invention isapplicable. One of such devices is a rocket engine.

A typical rocket engine operating cycle is as follows: If the engine ispump-fed, the oxidizer and fuel from the propellant tanks enter the lowpressure side of their respective turbo pumps. The turbo pumps can beeither of the axial or the centrifugal type, and are driven by a hot gasmulti-stage turbine. The hot gases are produced by a gas generator whichis essentially a small combustion chamber supplied by propellants tappedoff either side of the high pressure turbo pump discharge.Alternatively, the turbine may be driven using hot gases tapped offdirectly from the main combustion chamber. The turbo pumps supplypropellants at high pressure to the main combustion chamber.Alternately, the propellants may be supplied using only the propellanttank ullage pressure and acceleration head instead of a turbo pump. Inany case, the fuel and oxidizer are kept physically separated prior toentering the main chamber by the use of appropriate manifolds. Beforeentering the combustion chamber, the propellants are fed through anessential hardware item known as the injector. The injector is simply astructure which regulates and controls the flow of propellants. This isaccomplished normally by the use of a large number of small flowpassageways located within the injector. The use of small passagewaysproduces a fine spray pattern and therefore provides good combustionefficiency. In addition, the flow passages can be oriented so as toimpinge streams of oxidizer and fuel upon one another in variouspatterns to further aid in breaking up the propellant streams into smalldroplets. In theory, a rocket engine main combustion chamber wouldoperate normally and safely using a straightforward injector design.This, however, is not the case. The injector, rather than being a simpleslab of steel filled with holes, is the most sensitive and critical partof a rocket engine. This is because the injector almost exclusivelydetermines whether or not the combustion chamber operates under stableconditions. The essential ingredients for the existence of combustioninstability is organization of related combustion and thermo-dynamicprocesses. For example, one predominant mode of instability consists ofa pressure wave bouncing back and forth across the combustion chamber,reflected off the interior chamber walls in much the same way an echo isreflected off a flat surface. The pressure wave becomes harmful onlywhen an energy source is available at the proper time to sustain andintensify the wave. As a mild pressure wave propagates through theunburned propellant spray, the local increase in pressure along the wavecauses a local increase in the burning rate. The increase in burningrate is delayed by a short period of time, governed by the localthermo-dynamic condition and the specific chemical reactions that areinvolved. All chemical reactions require a finite time to release energyafter ignition. The time delay allows a zone of high energy release toform behind the original pressure wave. The pressure wave thereforeincreases in velocity and intensity, which in turn further increases thedriving energy force, thereby establishing a boot strap type process.The pressure wave quickly builds up to a strong supersonic shock. Atthis point, the combustion chamber pressure is completely out of controland the rocket engine will be destroyed in rather short order if notshut down by an emergency detection system. The important question toconsider therefore is as to how combustion instability can be prevented.

One semi-successful approach has been to attach baffles to the injectorface so that the baffles break up oncoming pressure waves. Baffles arecombined with a trial-and-error injection hole pattern to attempt toeventually develop a workable design. This approach is time-consumingand expensive.

The most logical and straightforward approach to solving the combustioninstability problem is to eliminate the problem source, that is, thepressure wave driving force which derives its energy from the combustionprocess. Since the energy wave is a local phenomenon, the wave must bedestroyed locally. This cannot be accomplished using current injectordesign techniques, since the spray pattern is fixed and continuouslysupplies a uniform, constant propellant flow rate into the combustionchamber volume such that the driving force energy source is alwayspresent in the form of unburned propellants. If, however, by some meansit is possible to change the propellant spray pattern when a pressurewave starts to build up, then the propellant energy can be used todestroy the pressure wave and thereby prevent its intensification. Thisis the approach employed by the present invention.

By computing the rate of pressure wave propagation through the unburnedpropellants and then relating the wave motion to the combustion chambergeometry, it is possible to locate pressure taps in the injector facewhich sense a local differential pressure within the combustion chamberand then this pressure is used to activate a fluid amplifier device toredistribute the propellants so as to break up the pressure wave. Such adesign would make a rocket engine inherently stable.

Referring now to FIGS. 1, 2 and 3, 11 generally designates thecombustion chamber and thrust chamber assembly assocaited with a typicalrocket engine. The assembly 11 is provided with improved fluid amplifierinjector means according to the present invention, presently to bedescribed.

The assembly 11 comprises the combustion chamber 12 and the thrustchamber 13 connected to the combustion chamber 12 by way of the annularconvergent wall 14 leading through the throat portion 15 to the flaringannular wall 16 of the thrust chamber 13.

The assembly 12 is provided with the oxidizer dome 17 adapted to receivesuitable oxidizer fluid from an oxidizer supply conduit 18. The oxidizeris supplied under pressure to the conduit 18 from a conventionaloxidizer pump or other pressure source, not shown. The oxidizer isdelivered into the interior of the dome 17, the interior space of dome17 being shown at 19. Space 19 is defined between the dome I7 and atransverse partition wall 20. The housing of the chamber 12 includes apair of transverse plates 21 and 22 secured together and spaced from thepartition wall 20, defining a fuel manifold space 23. Fluid fuelmaterial is admitted to the space 23 from a supply conduit 24 connectedthereto, as shown in FIG. 1, the fluid fuel material being furnishedfrom a suitable conventional fuel pump or other pressure source, notshown.

As shown in FIG. 2, the transverse plate 21 is formed with a pluralityof oxidizer passages 25, connected with the oxidizer space 19 byconduits 26 extending between partition wall 20 and plate 21 andtraversing the space 23. The passages 25 communicate with divergingouter passage portions 27, 28.leading to the combustion chamber 12.

As shown in FIG. 2, the plates 22 and 21 are formed to define auxiliarypassages 30 extending transverse to the main oxidizer passages 25 andterminating in detector ports 31, 31 spaced away from and located onopposite sides of the pair of divergent outlet passage portions 27, 28.

In a similar manner, the plate 21 is formed with fuel injection passages32, each leading to a pair of divergent outlet portions 33 and 34discharging into the combustion chamber 12. The plates 21 and 22 areformed to define transverse auxiliary passages 35 having end portions36, 36 exposed to the combustion chamber 12 at locations spaced awayfrom and located on opposite sides of the divergent outlet portions 33,34. The auxiliary passages 30 and 35 with their end portions 31, 31 and36, 36 serve to control the mainstream oxidizer injectors, passages 25,and the mainstream fuel injectors, passages 32, by responding to localabnormal pressure conditions in the combustion chamber 12. The sets ofoxidizer ports 27, 28 and their associated fluid pressure amplifierelements 30, 31, 31 and the fuel ports 33, 34 and their associated fluidamplifier elements 35, 36, 36 are distributed over the connectedpartition plates 21, 22 in any suitable manner, for example, inconcentric groups, as shown in FIG. 3, and are oriented in differentdirections so as to be able to sense pressure waves regardless of thedirections in which the waves are traveling.

Under normal operating conditions, the propellants, namely, the oxidizerand the fuel, will randomly flow through either of their associated setsof divergent outlet passage portions 27, 28 and 33, 34, but will notflow through both divergent passages. Thus, the oxidant passing throughone of the conduits 26 will normally flow through one of the divergentoutlet passage portions 27 or 28. Similarly, fuel flowing through apassage 32 will normally flow through one of the associated divergentoutlet passage portions 33 or 34. When a pressure wave travels acrossthe face of the injector plate 22, those switching ports or passages 31and 36 at or near right angles to the pressure wave are able to sensethe wave and automatically provide reactions in their associatedpassages 30 and 35 which will switch the propellants, changing the flowof the propellants through the divergent outlet passages in a manner toso distribute the propellants in front of the wave as to destroy thewave. For example, assume that fuel is flowing normally through thelower passage 32 and the upper divergent passage portion 33 in FIG. 2.Further assume that a pressure wave develops causing a low pressurecondition to be sensed by the lower fluid amplifier detection port 36 inFIG. 2. This low pressure condition is transmitted to the passage 35,thereby inducing a shift of the flow of fuel from the upper outletpassage portion 33 to the lower outlet passage portion 34 whichdischarges into the region adjacent to the sensed low pressure. Thedischarge of fuel into this region immediately raises the pressure andthereby eliminates the low pressure condition. The effect is to break upand destroy the incipient pressure wave.

The pressure sensing taps 36 and 31 are located sufficiently far fromthe propellant injection ports so as to be able to sense the wave earlyenough for the propellant redistribution to be successful.

FIGS. 1, 2 and 3 are merely representative of one typical arrangementemploying fluid amplifier pressure wave detection means in accordancewith the present invention. An infinite number of discharge portdistribution patterns are possible, all of which could be equallysuccessful. For example, the conventional type of fuel injection portsmay be employed in conjunction with oxidizer ports, such as the ports27, 28, provided with fluid amplifier sensing means 30, 31, 31.Conversely, conventional oxidizer injection ports may be employed inconjunction with fuel injection ports including the discharge portions33, 34, provided with fluid pressure amplifier wave detection means 35,36, 36.

Additionally, the fluid pressure wave sensing and dissipating meansabove described may be employed in conjunction with apparatus usingmonopropellants instead of bipropellants described in connection withFIGS. 1, 2 and 3. Furthermore, the injector portion of the engine orother device could be of any suitable shape, for example, could beannular in shape instead of being circular as illustrated in FIGS. 1, 2and 3.

As above described, the action of the fluid pressure detection means isto perform a switching action in the discharge of the associated fluidin a sense required to compensate for the abnormal pressure conditionssensed in this region. As above explained, when a lower pressurecondition is sensed by the lower fluid amplifer sensing port 36 itproduces a switching of the fuel from the upper branch 33 to the lowerbranch 34, causing discharge of fuel into the lower pressure region.Similarly, if the fuel is normally flowing through the lower branch 34,a high pressure sensed by the lower sensing port 36 will switch the fuelto the upper branch 33, reducing the pressure in the sensed region. Theoverall effect is therefore to damp out or attenuate fluctuations inpressure in the combustion chamber. The stabilizing or damping effect isaccomplished by controlling the path of movement of the associatedoxidizer or fuel fluid in a manner to provide improved stability ofoperation of the device. The general concept utilized in the rocketengine combustion chamber and thrust chamber assembly 11 of FIGS. 1, 2and 3 may be extended so as to be applicable in connection with manyother devices, for example, domestic or industrial fuel burners. Thegeneral function of a burner is to provide a means of facilitatingcombustion in order to provide a heat energy source. This heat energycan then be used for anything from a small home heater to a largeindustrial power plant boiler: From a power mower engine to an aircraftengine. Regardless of the intended use, the design of a burner is alwaysoriented toward achieving the maximum amount of combustion efficiency.This is in contrast to the design objective of a rocket engine where,although efficiency is desirable, the prime criterion is alwaysstability. The main reason for desiring stability in the design of aburner is to insure that the flame will not become extinguished. Theproblem of combustion instability is not so much a factor in the case ofordinary domestic or industrial burners as in the operation of rocketengines, the main factor in the case of domestic or industrial burnersbeing that of efficiency of combustion.

There is, of course, an upper limit to combustion efficiency for aburner. Complete combustion is theoretically attained when all of theavailable fuel is completely oxidized. In addition, the ratio of thefuel burned to the amount of oxidizer required for burning directlyinfluences the theoretical combustion temperature. At a unique ratio offuel to oxidizer, the theoretical combustion temperature is a maximumand occurs for a fuel-oxidizer mixture for which there is exactly theproper amount of oxidizer to react with the available fuel. This mixtureratio which results in maximum temperature is referred to as thestoichiometric condition. Stoichiometric combustion is desirable forfuel and oxidizer requirements combined with maximum energy releases,and therefore, maximum efficiency. To achieve complete combustion, it isgenerally neces sary to burn the fuel with an excess amount of oxidizer.This must be done since it is extremely difficult to completely mix thefuel and oxidizers so that a truly complete reaction can occur. Suchattempts usually result in a lower than desired temperature, as well asexcessive requirements for oxidizer. The problem of attaining maximumefficiency, therefore, reduces to the simple but elusive objective ofobtaining maximum effective mixing. In addition, this mixing of the fueland the oxider should occur at the stoichiometric mixture ratio. Unlessthese conditions are met, the temperature advantage of stoichoimetricburning cannot be realized. A number of burner designs are available forspecific applications. Either liquid or gaseous fuels may be employed.The gas burners may operate using either a high or low pressure fuelsupply. Liquid fuel burners are categorized into four groups as follows:

a. Self-atomizing burners.

b. Air-atomizing burners.

c. Steam-atomizing burners.

d. Mechanical-atomizing burners.

The objectives of each of the burner types are the same, that is, toprovide maximum fuel atomization over a wide flow rate requirementrange, to minimize excess oxidizer requirements and to provide both acost and maintenance advantage. Self-atomization is accomplished byforcing the liquid fuel under pressure through a restriction which tendsto form a spray. This approach is simple but requires a higher thandesirable fuel supply pressure, in addition to a large amount of excessoxidizer. Air-atomization is accomplished using the energy of compressedair (oxidizer) to break up the liquid fuel. The method is impracticaland is not used except for special applications simply because acompressed air facility is expensive. Also, the air required foratomization is in excess of that needed for efficient combustion. Steamatomization is accomplished using the energy of the steam to break upthe liquid fuel. Since the steam is substantially hotter than compressedair and lower in molecular weight, a much smaller amount of steam isrequired, compared to using air. Also, since only heat is needed forproducing steam in contrast to mechanical compression equipment neededfor air, the steam atomization approach has a distinct advantage overair atomization. Even so, the steam saps energy from the system for itsproduction and cannot actively participate in the combustion process toproduce useful energy. Lastly, mechanical atomization is accomplishedusing a moving mechanical device to break up the liquid fuel. Either thefuel must be at a sufficiently high pressure to propel the mechanicaldevice, or a separate power supply must be provided. In either case, themechanical parts reduce the burner reliability and lifetime. Lowpressure gas burners are relatively simple and are used for mostdomestic applications. The gas is delivered through a multi-outletmanifold to aid in mixing the gas and the oxidizer. The air is suppliedby natural convection caused by the heat of combustion. Both efficiencyand capacity are low.

High pressure gas burners are somewhat more sophisticated than the lowpressure type burners and are also more efficient because the gaspressure can be used to provide better gas-air mixing, although someexcess air is still required.

Having briefly described the burner designs available in the prior art,it will be now explained how the present invention utilizes a completelynew approach to burner design. Reference is therefore now made to FIGS.4 and 10 which diagrammatically illustrate burners according to thepresent invention, utilizing a fluid amplifier structure, designatedgenerally at 40 or 40'. The burner assembly, designated generally at 41,typically employs gas fuel, provided from a supply conduit 42 through agas valve 43 to a conduit or passage 44 leading to a pair of divergentoutlet passage portions 45 and 46 discharging into a combustion space47. As shown in FIG. 4 or 10, the upper passage 45 is provided with afluid amplifier by-pass passage 48 connecting a region 49 at the forwardend of the common junction of the divergent outlet passage portions 45and 46 to a region 50 spaced a considerable distance along passageportion 45. Similarly, the lower outlet passage portion 46 is providedwith a by-pass passage 51 connecting the region 49 to a region 52located a considerable distance from region 49 in the outlet passageportion 46.

When the gas valve 43 is opened, gas flows into the unit through thepassage or conduit 44 and flows through the space 49, entering one orthe other of the outlet passage portions 45 or 46. For example, assumingthat the gas stream enters the passage 45, the dis charge into the space47 will be through the outlet end of passage 45. Some of the gas isby-passed and fed back from region 50 through passage 48 and is injectedinto the space 49. This causes the gas stream to flip from passage 45 topassage 46, thus shifting the output of gas from the upper passage ofFIG. 4 or 10 to the lower passage discharging into space 47. A similaraction occurs by the operation of the by-pass passage 52, returning thegas stream to the upper passage 45 in FIG. 4 or 10. Therefore, theoutput stream oscillates between outlet passage portions 45 and 46 at arelatively high frequency, for example, at a frequency as high as 1,000cycles per second. The oscillation of the gas stream between the outletpassage portions 45 and 46 produces a many-fold increase in availablefuel surface area exposed to the air, as compared to that obtained byconventional designs. Since the burning rate is directly related to thesurface area, the combustion is accomplished more rapidly and thereforemore efficiently than in such previous designs. Also, the fluidamplifier type burner 41 has a unique feature not found in any of theother burner types. This feature is that the fuel is mixed into theoxidizer, as opposed to mixing the oxidizer into the fuel. The burnercan use liquid for fuel instead of gas fuel, if desired. Fuel supplypressure can be either high or low. Since no moving parts are needed,the lifetime of the burner is indefinite. Also, since compressed air,steam boilers, power supplies, or other elaborate equipment is notrequired, the cost of the installation is comparatively low.

There are many potential applications for which burners of the typeshown diagrammatically in FIG. 4 or 10 may be employed. For example,such burners can be employed in domestic appliances such as furnaces,refrigerators, clothes dryers, kitchen ranges, air conditioning unitsand water heaters. Also, this type of burner may be employed in largeindustrial applications, for example, in devices employing multipleburners, for example, a multiple-burner arrangement such as thatillustrated diagrammatically in FIG. 6.

Thus, as shown in FIG. 6, the burner assembly may comprise a single fuelsupply manifold 60 feeding a plurality of successive fluid amplifierburner units, each comprising a main supply inlet passage 61 providedwith divergent outlet passage portions, said passage portions beingprovided with respective fluid amplifier by-pass passages. This producesan oscillatory effect described above in connection with the single unitillustrated in FIG. 4 or 10.

FIG. 5 diagrammatically illustrates another possible application of theimproved oscillating burner arrangement of FIG. 4 or 10 employed in thefuel mixture supply system associated with the cylinder 70 of aninternal combustion engine. Thus, the gas-air supply manifold 71communicates with the divergent outlet passage portions 72 and 73 whichdischarge into the combustion space 74 of the cylinder. The passageportion 72 is provided with a fluid amplifier by-pass passage 75connecting the junction space 76 with a region spaced a substantialdistance along passage portion 72. Similarly, a fluid ampliifer by-passpassage 77 connects the space 76 to a region spaced a substantialdistance along the other passage portion 73. The arrangement shown inFIG. provides an oscillating action similar to that described inconnection with FIG. 4 or 10, and thereby provides greatly improvedefficiency of combustion of fuel in the combustion space 74 of cylinder70.

FIG. 7 illustrates another typical application using the fluid amplifierprinciple employed in connection with FIGS. 4, 10, 5 and 6. Thus, inFIG. 7 air or steam is admitted into a burner 80 through a conduit 81located coaxially in a chamber 82 through which fuel oil is supplied,leading to a junction space 83 from which the divergent outward passageportions 84 and 85 extend, discharging into a combustion chamber 86. Itwill be seen from FIG. 7 that mixture of the air or steam with the fueloil takes place essentially in the junction space 83. The mixture thenflows either through passage 84, or 85, toward the combustion chamber86.

Passage 84 is provided with by-pass fluid amplifier passage 87 whichconnects space 83 to a region 88 located a substantial distance alongpassage 84, and similarly, a fluid amplifier by-pass passage 89 connectsjunction region 83 to a region 90 located a substantial distance alongthe outward passage portion 85. The burner device of FIG. 7 operates ina manner generally similar to that described above in connection withFIGS. 4 or 10, 5 and 6, providing an oscillation action which alsoresults in a substantial increase in efficiency of combustion, for thereasons given above.

FIG. 8 is another example of a burner, according to the presentinvention, using fluid amplifier principles; but wherein the mixture ofthe fuel and oxidant occurs substantially externally of the burner unit.Thus, 91 generally designates the burner unit in FIG. 8, said unitcomprising a housing 92 to which the fuel is admitted, for example, oil.Mounted in the housing 92 is a chamber 93 into which the air or steam isadmitted, the air or steam flowing through a conduit passage 94 towardajunction space 95 defined between a pair of divergent outlet passageportions 96 and 97 integrally-formed with the member 93 and discharginginto a combustion space 98. As shown in FIG. 8, the walls of the housing92 extend around, but are spaced from the corners 99,

99 of the member 93, defining respective outlet passages I00 and 101through which the fuel oil is injected into the combustion space 98. Therespective air or steam outlet passage portions 96 and 97 are providedwith fluid amplifier by-pass passages 102 and 103 connecting junctionspace 95 to regions spaced substantial distances along the outletpassage portions, for example, to regions I04 and 105 shown in FIG. 8.The fluid amplifier passages I02, I03, therefore, provide an oscillationaction on the air or steam stream, flipping the stream between thepassages 96 and 97 in a manner similar to that described above inconnection with FIG. 4 or 10. This provides efficient mixing of the airor steam with the fuel discharging into thecombustion space 98 throughthe discharge passages 100 and 101,

and the generation of great turbulence in the combustion space 98,therefore, results in greatly increased over-all combustion efficiency,for the reasons stated above. When steam is used as the fluid in theflow conduit 94, the oxidizer, usually air, is external to the burnerassembly and burns with the turbulent steam-oil mixture in thecombustion space 98.

FIG. 9 illustrates another modification of a fluid amplifier-type ofburner, according to the present invention. Thus, the burner isdesignated generally at and comprises a block 111 to which is connecteda gassupply conduit 112 through a valve 113 leading to a junction space114 in block 111. The divergent outlet passage portions 115 and 117 leadto a discharge space 117 from the junction space 114. By-pass fluidamplifier passages 118 and 119 connect junction space 114 to regions 120and 121 spaced considerable distances along the passages 115 and 116from the junction space 114. The burner is supplied with oxidant,namely, air through supply conduits 122, 122 connected to the block 111and connected by passages 123, 123 to the space 114 ahead of theconnections of the bypass passages 118, 119 thereto. The air may bemerely aspirated into the burner from the supply conduits 122, 122, oralternatively, may be introduced under pressure. The fuel and the airare primarily mixed in the junction space 114, but secondary mixingoccurs in the ignition space 117, which may be exposed to the ambientair. The fluid amplifier by-pass passages 118, 119 provide anoscillating action, as described above in connection with FIG. 4 or 10,which promotes the efficient combustion of the air-fuel mixture for thereasons described above.

As above mentioned, the air admitted through the conduit 122 may beunder ordinary atmospheric pressure and may be aspirated into theburner, or alternatively, can be supplied under pressure, if so desired.

In accordance with the present invention, the oscillating jetarrangement employed in the devices illustrated in FIGS. 4 to 10 may beemployed in combination with pressure wave-control ports similar tothose illustrated in FIGS. 1, 2 and 3. Thus, a random sprinkling ofoscillator devices such as that shown in FIG. 4 or 10, or in FIGS. 5 to9, may be employed among the pressure wave-control configurationsillustrated in FIGS. 1, 2 and 3.

As above-mentioned, the fluid amplifier-type of fuel combustion devicedescribed above may be employed in many types of apparatus, for example,in automobile engines in the manner illustrated in FIG. 5. With suchapplications, not only is efficiency of combustion obtained in a moreefficient manner, but also greatly increased safety, since the morecomplete combustion substantially eliminates practically all of thecarbon monoxide. Also, the complete combustion of the fuel reduces theformation of carbon and soot. It will thus be understood that the fluidamplifier-type of burner described above could be advantageouslyemployed as an air pollution-control device and may be employed incombination with conventional burners so as to obtain the advantages ofconventional burners along with those of the fluid-amplificr-type ofburner. In certain applications, where cost is not an important factor,compressed air or steam energy can be employed to complement the energyof the oscillating stream in order to obtain the ultimate in combustionefficiency.

Although no mention was made of the method of ignition of the fuel inthe device shown in FIG. 1, such ignition may be accomplished in anyconventional manner, for example, by an electric spark plug, byhypergolic reaction (ignition on contact without further addition ofenergy), or by a pyrotechnic igniter device or by another flame.

In connection with FIG. 2, it should be understood that since thepropellants are liquids, when they pass through the amplifier injectionsection, the control ports 31, 36 may initially dribble some of thepropellants into the combustion chamber. As the pressure builds up inthe chamber, the gas pressure then controls the main propellant streamsby sensing the pressure on either side of each amplifier.

As above-mentioned, the fluid amplifier burner arrangement of FIG. 4 ormay be employed in combi- -nation with the control amplifier arrangementof FIGS.

1, 2 and 3, or the oscillating type of stream action of FIG. 4 or 10 maybe employed entirely in structures such as that of FIGS. 1, 2 and 3.Thus, the configuration of the fluid amplifier of FIG. 4 or 10 may besubstituted for that of FIGS. 1, 2 and 3. Thus, an injector can be madewholly of oscillator elements, or a combination of oscillator elementsand pressure-control elements. The injector shown in FIG. 6 is a typicalexample of one comprising only oscillator elements.

In the case of FIG. 5, this shows an oscillator amplifier devicearranged for the distribution of fuel into the internal combustionchamber 74 with pre-mixing having occurred prior to said distribution,the pre-mixed fuel traveling through the manifold 71. Obviously, thestructure of FIG. 5 may also represent that required for distributingthe fuel directly into the internal combustion chamber 74 from themanifold 71 with the oxidizer (generally air) provided through one ofthe valves, for example, through the valve 113. It should also be notedthat an oscillator element may be employed upstream of the oscillatorinjector to initially pre-mix the fuel and air before the mixture entersthe manifold 71 to feed the oscillator injector comprising the elements72, 75 and 73, 77. Thus, complete mixing and intermixing may require thefuel and oxidizer (air) to pass through a series of oscillators prior tofinal injection into the cylinder.

FIGS. 11, 12 and 13 show examples of the application of fluid amplifierinjector devices as above described to jet engines. FIG. 11diagrammatically shows in longitudinal vertical cross-section a typicalcan structure jet engine burner, designated generally at 130, generallysimilar to current design but employing the principle of the fluidamplifier injector devices, as above described. The assembly 130comprises an elongated main housing 131 having a compressed air inletduct 132 at one end and having a jet outlet duct 133 at its other end. Aburner assembly, designated generally at 134, is mounted in theintermediate portion of the housing 131 and is spaced from the wallsurfaces of said housing to define an annular cooling air flow space 136between the burner assembly 134 and the housing. The burner assembly 134is mounted substantially axially in the elongated main housing 131, andcomprises a casing 137 having an arcuately curved longitudinal contour,the casing being provided with a transverse partition wall 138 locatedadjacent its left, or upstream, end and defining a combustion space 139to the right thereof, namely, at the downstream side thereof. A

conduit 140 leads from a source of fuel under pressure to a fluidamplifier injector unit 141 centrally located in the partition wall 138.A plurality of fluid amplifier air injector units 142 are provided inthe partition wall 138, spaced around the central fluid amplifierinjector unit 141.

The wall of the casing 137 surrounding the combustion space 139 isformed with a plurality of fluid oscillator ports, shown at 143, saidports comprising passages having diverging inner branches leading to thecombustion space 139, for bleeding airinto the combustion space withoscillator action to provide additional turbulence and to stimulate andreinforce the combustion action.

As above mentioned, the fuel under pressure is injected into thecombustion chamber 139 through the fluid amplifier injector unit 141.Primary air from the compressor discharge is furnished through theintake duct 132, and is injected into the combustion space 139 throughthe fluid amplifier injector passage systems 142, so as to mix with thefuel inside the casing 137. Secondary air, also from the compressordischarge, circulates past the exterior of the casing 137 so as to coolthe casing. Some of the secondary air bleeds through the fluid amplifierinjector devices 143 in the wall of the casing to aid in the combustionprocess.

In a jet engine, it is essential that the unburned cool air be mixedwith the hot products of combustion before the mixture enters theturbine. Poor mixing causes hot spots on the turbine. The use of thefluid amplifier injector units, in addition to allowing a higherefficiency of burning to be provided, caused by more efficient mixing,also provides for a more uniform mixture of combustion products and airthrough the turbine. The efficient combustion results in a reduction inspecific fuel consumption, and the more uniform mixing extends theuseable life of the turbine, which is a significant maintenance factor.

The modification illustrated in FIG. 12 employs the same principles asthat of FIG. 11 but is somewhat different in geometrical structure. InFIG. 12, the assembly, shown generally at 150, has a longitudinalcenterline 151, the figure showing only one-half the structure above,namely, that above the centerline 151. The main housing, shown at 152,has an air inlet duct at 153 and a jet outlet duct at 154. The burnercasing, shown at 155, is of annular configuration and has an inwardlytapering coaxial upstream end portion 156 which is exposed to the airinlet duct 153. The cross-sectional shape of the casing also includesinwardly tapering air bleeder portions 157 similarly exposed to thecompressed air intake duct 153, as shown.

The casing is provided with fuel manifolds 158 communicating throughfluid amplifier injector units 159 with the left end regions of thecasing 155, for injecting fuel into the casing in the direction of thecombustion space 160 thereof. The casing 155 is spaced from the mainhousing 152 to define an annular cooling air flow space 161, as in theform of the engine illustrated in FIG. 11. The walls of the casing areprovided with secondary air injector passages 143 similar to those ofFIG. 11, comprising ports provided with diverging inner branches leadingto the combustion space 160.

Fuel and air are injected in an annular pattern around the enginecenterline 151, with the combustion taking place in the space 160 in amanner similar to that occurring in the embodiments of FIG. 11. Themodification of FIG. 12 allows for a higher air flow rate than that ofFIG. 11, since more surface area of the casing is available for airinjection.

The further modification illustrated in FIG. 13 is generally similar inprinciple and design to the modifications of FIGS. 11 and 12. In FIG.13, the assembly is generally indicated at 170 and the main housingthereof is shown at 171. The elongated main housing 171 is provided withthe air inlet duct 172 and the jet outlet duct 173. The burner casing,shown at 174, is coaxially mounted in the main housing and has thegenerally forwardly flaring wall configuration defining an internalcombustion space 175. The upstream, or forward, end portion of thecasing 174 is provided with the inwardly projecting tapered coaxialportion 176 centrally exposed to the compressed air intake duct 172, asshown. The upstream end portion of the casing 174 is provided with thefuel supply manifolds 177 similar to the manifolds 158 of FIG. 12. Thecasing 174 is spaced from the enlarged central portion of the mainhousing 171 to define an annular cooling air flow space 178 between theburner casing 174 and the main housing 171. The walls of the burnercasing 174 are provided with spaced secondary air oscillator injectorports 143 similar to those employed in the embodiments of FIGS. 11 and12, namely, comprising passages having divergent inner branches leadingto the combustion space 175.

In the embodiments of FIG. 13, the fuel and air. are injected in anannular pattern around the center line of the engine unit 170. Aplurality of units 170 may be clustered around the main engine centerline to form individual burner modules. Thus, this arrangement combinesthe best features of the relatively compact embodiments of FIG. 11 andthe relatively bulky embodiments of FIG. 12, providing excellentefficiency and convenient maintenance.

The phenomenon of surge frequently causes serious problems in jetengines. The embodiments illustrated in FIGS. 11, 12 and 13 tend toeliminate or to greatly reduce surge problems.

From the above discussion, it will be evident that a large number ofpossible fuel and air injection patterns or arrangements may be devised,all employing the principles inherent in the present invention.

While certain specific embodiments of an improved structural arrangementfor controlling the flow of fluid to use in combustion in a manner toimprove or stabilize combustion have been disclosed in the foregoingdescription, it will be understood that various modifications within thespirit of the invention may occur to those skilled in the art.Therefore, it is intended that no limitations be placed on the inventionexcept as defined by the scope of the appended claims.

What is claimed is:

1. In combination, means defining a combustion space, a source of fluidto be utilized in combustion in said space, and means defining a supplyflow passage from said source leading to said space, said meanscomprising a main supply passage portion connected to said source, apair of diverging discharge passage portions leading from said mainpassage portion to said combustion space and opening into saidcombustion space at spaced locations therein, and means definingauxiliary passage portions connected between the junction of thediverging passage portions and respective regions in communication withthe combustion space and located substantial flow distances downstreamfrom said junction, whereby said auxiliary passage portions act as fluidamplifier pressure sensors and react on the fluid stream passing saidjunction to direct the flow of the fluid through one or the other ofsaid diverging passage portions in accordance with the pressures at saidrespective regions, wherein said combustion space includes a boundarywall, said diverging discharge passage portions and said auxiliarypassage portions being formed in said boundary wall.

2. The structural combination of claim 1, and wherein the downstreamends of said auxiliary passage portions are located adjacent thedownstream ends of the diverging discharge passage portions.

3. The structural combination of claim 2, and

wherein the downstream ends of said auxiliary passage portions areexposed directly to the combustion space.

4. The structural combination of claim 3, and wherein the downstreamends of said auxiliary passage portions are located outwardly adjacentthe downstream ends of said diverging discharge passage portions.

5. The structural combination of claim 1, and wherein said boundary wallis provided with a plurality of said supply flow passage meansdistributed thercover and wherein the downstream ends of the auxiliarypassage portions thereof are located to detect pressure waves in thecombustion space.

6. The structural combination of claim 5, and wherein said supply flowpassage means are arranged in concentric groups in said boundary wall.

7. The structural combination of claim 4, and wherein the downstreamends of the auxiliary passage portions and the diverging dischargepassage portions are located substantially in the same plane.

8. In combination, means defining a combustion space, a source of fluidto be utilized in combustion in said space, and means defining a supplyflow passage from said source leading to said space, said meanscomprising a main supply passage portion connected to said source, apair of diverging discharge passage portions leading from said mainpassage portion to said combustion space and opening into saidcombustion space at spaced locations therein, and means definingauxiliary passage portions connected between the junction of thediverging passage portions and respective regions in communication withthe combustion space and located substantial flow distances downstreamfrom said junction, whereby said auxiliary passage portions act as fluidamplifier pressure sensors and react on the fluid stream passing saidjunction to direct the flow of the fluid through one or the other ofsaid diverging discharge passage portions in accordance with the pressures at said respective regions, wherein the downstream ends of saidauxiliary passage portions are located adjacent the downstream ends ofthe diverging discharge passage portions, and wherein the downstreamends of the auxiliary passage portions communicate with the respectivediverging discharge passage portions at points in said discharge passageportions spaced substantial flow distances from said junction, wherebyto cause the flow stream to oscillate discretely between the divergentdischarge passage portions.

9. The structural combination of claim 8, and wherein the upstream endsof said auxiliary passage portions are diametrically-opposite each otherand are substantially coplanar with said junction.

10. The structural combination of claim 9, and wherein said combustionspace includes a boundary wall, said boundary wall being provided with aplurality of said supply flow passage means distributed thereover, andwherein said divergingdischarge passage portions and said auxiliarypassage portions are formed in said boundary wall.

11. The structural combination of claim 10, and wherein said boundarywall is formed with a supply manifold communicating with the main supplypassage portions of the supply flow passage means.

12. In a jet engine, an elongated main housing having a compressed airinlet duct at one end and having a jet outlet duct at its other end, aburner assembly mounted in the intermediate portion of said housing andbeing spaced from the wall surfaces of the housing to define a coolingair flow space between the burner assembly and the housing, said burnerassembly comprising a casing defining a combustion space, a source offluid to be utilized in combustion in said combustion space, meansdefining a supply flow passage from said source leading to saidcombustion space, said means comprising a main supply passage portionconnected to the source, a pair of diverging discharge passage portionsleading from said main passage portion to said combustion space andopening into said combustion space at spaced locations therein, andmeans defining auxiliary passage portions connected between the junctionof the diverging passage portions and respective regions incommunication with the combustion space and located substantial flowdistances downstream from said junction, whereby said auxiliary passageportions act as fluid amplifier sensors and react on the fluid streampassing said junction to direct the flow of the fluid through one or theother of said diverging passage portions in accordance with thepressures at said respective regions, said combustion space including aboundary wall, said diverging passage portions and said axuiliarypassage portions being formed in said boundary wall.

13. The jet engine of claim 12, and wherein the wall of the casing isformed adjacent said combustion space with a plurality of secondary airinjection passages having divergent inner branches opening into thecombustion chamber for bleeding air into the combustion space.

14. The jet engine of claim 12, and wherein the downstream ends of saidauxiliary passage portions communicate with the respective divergingpassage portions at locations spaced downstream from said junction.

15. The jet engine of claim 14, and wherein the casing is locatedsubstantially coaxially in said main housing to define a substantiallyannular cooling air flow space between the casing and the main housing.

16. The jet engine of claim 15, and wherein the wall of the casingdefining the inner boundary of said cooling air flow space'is formedwith secondary air injector passages having divergent inner branchesleading to said combustion space.

17. in ajet engine, an elongated main housing having a compressed airinlet duct at one end and having a jet outlet duct at its other end, aburner assembly mounted in the intermediate portion of said housing andbeing spaced from the wall surfaces of the housing to define a coolingair flow space between the burner assembly and the housing, said burnerassembly comprising a casing defining a combustion space, a source offluid to be utilized in combustion in said combustion space, meansdefining a supply flow passage from said source leading to saidcombustion space, said means comprising a main supply passage portionconnected to the source, a pair of diverging discharge passage portionsleading from said main passage portion to said combustion space andopening into said combustion space at spaced locations therein, andmeans defining auxiliary passage portions connected between the junctionof the diverging passage portions and respective regions incommunication with the combustion space and located substantial flowdistances downstream from said junction, whereby said auxiliary passageportions act as fluid amplifier sensors and react on the fluid streampassing said junction to direct the flow of the fluid through one or theother of said diverging passage portions in accordance with thepressures at said respective regions, wherein the downstream ends ofsaid auxiliary passage portions communicate with the respectivediverging passage portions at locations spaced downstream from saidjunction, wherein the casing is located substantially coaxially in saidmain housing to define a substantially annular cooling air flow spacebetween the casing and the main housing, wherein the wall of the casingdefining the inner boundary of said cooling air flow space is formedwith secondary air injector passages having divergent inner branchesleading to said combustion space, and wherein said casing has aninwardly tapering coaxial upstream end portion exposed to saidcompressed air inlet duct and formed with air injector passages havingdivergent inner branches leading to said combustion space.

1. In combination, means defining a combustion space, a source of fluid to be utilized in combustion in said space, and means defining a supply flow passage from said source leading to said space, said means comprising a main supply passage portion connected to said source, a pair of diverging discharge passage portions leading from said main passage portion to said combustion space and opening into said combustion space at spaced locations therein, and means defining auxiliary passage portions connected between the junction of the diverging passage portions and respective regions in communication with the combustion space and located substantial flow distances downstream from said junction, whereby said auxiliary passage portions act as fluid amplifier pressure sensors and react on the fluid stream passing said junction to direct the flow of the fluid through one or the other of said diverging passage portions in accordance with the pressures at said respective regions, wherein said combustion space includes a boundary wall, said diverging discharge passage portions and said auxiliary passage portions being formed in said boundary wall.
 2. The structural combination of claim 1, and wherein the downstream ends of said auxiliary passagE portions are located adjacent the downstream ends of the diverging discharge passage portions.
 3. The structural combination of claim 2, and wherein the downstream ends of said auxiliary passage portions are exposed directly to the combustion space.
 4. The structural combination of claim 3, and wherein the downstream ends of said auxiliary passage portions are located outwardly adjacent the downstream ends of said diverging discharge passage portions.
 5. The structural combination of claim 1, and wherein said boundary wall is provided with a plurality of said supply flow passage means distributed thereover and wherein the downstream ends of the auxiliary passage portions thereof are located to detect pressure waves in the combustion space.
 6. The structural combination of claim 5, and wherein said supply flow passage means are arranged in concentric groups in said boundary wall.
 7. The structural combination of claim 4, and wherein the downstream ends of the auxiliary passage portions and the diverging discharge passage portions are located substantially in the same plane.
 8. In combination, means defining a combustion space, a source of fluid to be utilized in combustion in said space, and means defining a supply flow passage from said source leading to said space, said means comprising a main supply passage portion connected to said source, a pair of diverging discharge passage portions leading from said main passage portion to said combustion space and opening into said combustion space at spaced locations therein, and means defining auxiliary passage portions connected between the junction of the diverging passage portions and respective regions in communication with the combustion space and located substantial flow distances downstream from said junction, whereby said auxiliary passage portions act as fluid amplifier pressure sensors and react on the fluid stream passing said junction to direct the flow of the fluid through one or the other of said diverging discharge passage portions in accordance with the pressures at said respective regions, wherein the downstream ends of said auxiliary passage portions are located adjacent the downstream ends of the diverging discharge passage portions, and wherein the downstream ends of the auxiliary passage portions communicate with the respective diverging discharge passage portions at points in said discharge passage portions spaced substantial flow distances from said junction, whereby to cause the flow stream to oscillate discretely between the divergent discharge passage portions.
 9. The structural combination of claim 8, and wherein the upstream ends of said auxiliary passage portions are diametrically-opposite each other and are substantially coplanar with said junction.
 10. The structural combination of claim 9, and wherein said combustion space includes a boundary wall, said boundary wall being provided with a plurality of said supply flow passage means distributed thereover, and wherein said diverging discharge passage portions and said auxiliary passage portions are formed in said boundary wall.
 11. The structural combination of claim 10, and wherein said boundary wall is formed with a supply manifold communicating with the main supply passage portions of the supply flow passage means.
 12. In a jet engine, an elongated main housing having a compressed air inlet duct at one end and having a jet outlet duct at its other end, a burner assembly mounted in the intermediate portion of said housing and being spaced from the wall surfaces of the housing to define a cooling air flow space between the burner assembly and the housing, said burner assembly comprising a casing defining a combustion space, a source of fluid to be utilized in combustion in said combustion space, means defining a supply flow passage from said source leading to said combustion space, said means comprising a main supply passage portion connected to the source, a pair of diverging discharge passage portions leading from said main Passage portion to said combustion space and opening into said combustion space at spaced locations therein, and means defining auxiliary passage portions connected between the junction of the diverging passage portions and respective regions in communication with the combustion space and located substantial flow distances downstream from said junction, whereby said auxiliary passage portions act as fluid amplifier sensors and react on the fluid stream passing said junction to direct the flow of the fluid through one or the other of said diverging passage portions in accordance with the pressures at said respective regions, said combustion space including a boundary wall, said diverging passage portions and said axuiliary passage portions being formed in said boundary wall.
 13. The jet engine of claim 12, and wherein the wall of the casing is formed adjacent said combustion space with a plurality of secondary air injection passages having divergent inner branches opening into the combustion chamber for bleeding air into the combustion space.
 14. The jet engine of claim 12, and wherein the downstream ends of said auxiliary passage portions communicate with the respective diverging passage portions at locations spaced downstream from said junction.
 15. The jet engine of claim 14, and wherein the casing is located substantially coaxially in said main housing to define a substantially annular cooling air flow space between the casing and the main housing.
 16. The jet engine of claim 15, and wherein the wall of the casing defining the inner boundary of said cooling air flow space is formed with secondary air injector passages having divergent inner branches leading to said combustion space.
 17. In a jet engine, an elongated main housing having a compressed air inlet duct at one end and having a jet outlet duct at its other end, a burner assembly mounted in the intermediate portion of said housing and being spaced from the wall surfaces of the housing to define a cooling air flow space between the burner assembly and the housing, said burner assembly comprising a casing defining a combustion space, a source of fluid to be utilized in combustion in said combustion space, means defining a supply flow passage from said source leading to said combustion space, said means comprising a main supply passage portion connected to the source, a pair of diverging discharge passage portions leading from said main passage portion to said combustion space and opening into said combustion space at spaced locations therein, and means defining auxiliary passage portions connected between the junction of the diverging passage portions and respective regions in communication with the combustion space and located substantial flow distances downstream from said junction, whereby said auxiliary passage portions act as fluid amplifier sensors and react on the fluid stream passing said junction to direct the flow of the fluid through one or the other of said diverging passage portions in accordance with the pressures at said respective regions, wherein the downstream ends of said auxiliary passage portions communicate with the respective diverging passage portions at locations spaced downstream from said junction, wherein the casing is located substantially coaxially in said main housing to define a substantially annular cooling air flow space between the casing and the main housing, wherein the wall of the casing defining the inner boundary of said cooling air flow space is formed with secondary air injector passages having divergent inner branches leading to said combustion space, and wherein said casing has an inwardly tapering coaxial upstream end portion exposed to said compressed air inlet duct and formed with air injector passages having divergent inner branches leading to said combustion space. 